Informs 2015

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INFORMS Philadelphia – 2015
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2 - An Approximation for the Bed Occupancy Process in
Inpatient Wards
Ohad Perry, Northwestern University, 2145 Sheridan Road,
Evanston, IL, 60208, United States of America,
We consider queueing dynamics of bed-occupancy processes in inpatient wards.
These are time varying, and have departures that are highly concentrated within
a short time period each day, following the physicians’ daily inspection round. We
characterize a necessary and sufficient condition for the system to be stable, and
employ a fluid approximation to prove an asymptotic periodic behavior of the
system. That ``periodic equilibrium’’ can be used to optimize systems’
performance.
3 - Operations Management of a Stool Bank for
Fecal Transplantations
Abbas Kazerouni, Stanford University, Electrical Engineering
Department, Stanford, CA, United States of America,
Lawrence Wein
We describe our work with OpenBiome, a nonprofit firm that enables fecal
transplants for treating Clostridium difficile, which is responsible for 25,000
deaths and $1 billion annually in the U.S. We optimize the timing of new donor
acquisitions and the individualized (based on donor production rate) testing
frequency for each donor, with the goal of meeting nonstationary demand
(increasing at 10% per month) at minimum cost.
4 - Queues with Time-varying Arrivals and Inspections with
Applications to Hospital Discharge Policies
Carri Chan, Columbia Business School, 3022 Broadway, Uris Hall,
Room 410, New York, NY, 10027, United States of America,
, Linda Green, Jing Dong
To discharge a patient from a hospital unit, a physician must determine that the
patient is stable enough to be discharged. As such, patients may occupy a bed
longer than medically necessary. Motivated by this phenomenon, we introduce a
queueing system with time-varying arrival rates in which servers who have
completed service cannot be released until an inspection occurs. We examine how
such a dynamic impacts system dynamics and consider how to optimize the
timing of inspections.
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47-Room 104B, CC
MSOM Sustainability and Energy
Sponsor: Manufacturing & Service Oper Mgmt/Sustainable
Operations
Sponsored Session
Chair: Yangfang Zhou, Assistant Professor, Lee Kong Chian School of
Business, Singapore Management University, Singapore, Singapore,
1 - Investments in Renewable and Conventional Energy:
Role of Operational Flexibility
Kevin Shang, Duke University, 100 Fuqua Drive, Durham, NC,
United States of America, , Gurhan Kok,
Safak Yucel
We study investments of a utility firm in renewable and conventional energy
sources with different levels of operational flexibility, i.e., the ability to quickly
ramp up or down the output of a generator. We consider supply characteristics of
conventional and renewable sources to investigate their interaction with each
other. We find that inflexible sources (e.g., nuclear energy) and renewables are
strategic substitutes; flexible sources (e.g., natural gas) and renewables are
complements.
2 - Promoting Clean Technology Products: to Subsidize Consumers
or Manufacturer?
Ho-Yin Mak, University of Oxford, Said Business School, Park
End Street, Oxford, United Kingdom, ,
Guangrui Ma, Michael Lim, Zhixi Wan
We study the dynamic adoption process of Clean Technology Products, which is
often hampered by the chicken-and-egg dilemma: at the early stage of
commercialization, firms are reluctant to invest in support infrastructure before
sufficient consumers adopt the products; on the other hand, consumers hesitate
to adopt the products without such infrastructure. We study two lines of widely-
discussed policy instruments, government subsidies and mandated information
disclosure, to tackle this dilemma.
3 - Is Electricity Storage “GREEN”? A Case Study with Commercial
Buildings for Reducing Demand Charge
Yangfang Zhou, Assistant Professor, Lee Kong Chian School of
Business, Singapore Management University, Singapore,
Singapore,
Electricity storage systems, e.g., grid-scale industrial batteries, are known in the
literature to increase carbon emission when used for arbitrage. However, we
show that when these storage systems are used for reducing demand charge (on
peak load), they can potentially decrease carbon emission. We model the problem
of managing electricity storage and solar panels in a commercial building (e.g.,
those for hotels, banks, and supermarkets), and examine the “greenness” of
storage with real data.
4 - Dynamics of Capacity Investment in Renewable Energy Projects
John Birge, Professor, University of Chicago Booth School of
Business, 5807 S Woodlawn Ave, Chicago, IL, 60637, United
States of America, , Nur Sunar
We study the dynamics of the capacity investment for renewable power
generators. Using a continuous time Brownian model, we explicitly identify the
optimal dynamic capacity investment strategy of a renewable power generator.
Our analysis offers important insights for renewable power generators. We also
include some numerical analysis to shed light on the optimal strategy.
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48-Room 105A, CC
Supply Chain Finance and Risk Management
Sponsor: Manufacturing & Service Oper Mgmt/iFORM
Sponsored Session
Chair: Wei Luo, IESE Business School, Av. Pearson 21,
Barcelona, Spain,
Co-Chair: Kevin Shang, Duke University, 100 Fuqua Drive,
Durham, NC, United States of America,
1 - The Strategic Role of Business Insurance
Juan Serpa, Assistant Professor, Kelley School of Business,
Indiana University, 2111 Lower Mall, Bloomington, IN,
United States of America, ,
Harish Krishnan
We show that, in a multi-firm setting, insurance can be used strategically as a
commitment mechanism to prevent excessive free-riding by other firms. In the
presence of wealth imbalances, contracts alone leave wealth-constrained firms
with inefficiently low incentives to exert effort, and firms with sufficient wealth
with excessive incentives. Insurance allows the latter to credibly commit to lower
effort, thereby mitigating the incentives of the wealth-constrained firms to free
ride.
2 - Supply Chain Financing with Buy-back Contracts
Tunay Tunca, University of Maryland, College Park, MD,
United States of America,
Weiming Zhu
Facing a budget-constrained buyer, a novel approach for large suppliers is
adopting buy-back financing schemes to relieve their downstream partners and
reduce channel costs. We analyze the efficiency of these financing schemes, and
explore their impact on operational decisions and contract design. We find that
such contract agreements can improve channel efficiency significantly over
traditional financing methods.
3 - Supply Chain Network Formation and Risk Propagation
John Birge, Professor, University of Chicago Booth School of
Business, 5807 S Woodlawn Ave, Chicago, IL, 60637, United
States of America, , Jing Wu
The structure of supply chain networks impacts firm’s performance through direct
effects from shocks to linked firms as well as indirect effects from systematic risk
exposure across the entire network. This talk will discuss a motivating model of
network formation in this context and its implications for firms’ supply chain
choices.
4 - Trade Credit and Price Elasticity of Demand
Eduard Calvo, IESE School of Business, IESE, Barcelona, Spain,
, Wei Luo
This paper investigates how price elasticity of demand impacts trade credit in
virtually integrated supply chains. We derive a theoretical model wherein trade
credit is expressed as a function of margins, financing costs and elasticity. Ceteris
paribus, we predict that suppliers of products with higher demand elasticity
should be paid earlier to unlock higher profits. We further test the model using
data from a large Spanish supermarket chain and its virtually integrated suppliers.
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